#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>

int main()
{
	int n = 0;
	double ans = 0;
	scanf("%d", &n);
	for (int i = 1; i <= n; i++)
	{
		ans += 1 / (double)i;
	}
	printf("%lf", ans);
	return 0;
}